Index: configure.ac
===================================================================
--- configure.ac	(revision 169877)
+++ configure.ac	(working copy)
@@ -267,6 +267,16 @@ done
 tmake_file="${tmake_file_}"
 AC_SUBST(tmake_file)
 
+# Likewise export definitions for libgcc_tm.h
+tm_file_=
+for f in ${tm_file}
+do
+	tm_file_="${tm_file_} \$(srcdir)/config/$f"
+done
+tm_file="${tm_file_}"
+AC_SUBST(tm_file)
+AC_SUBST(tm_defines)
+
 # Substitute configuration variables
 AC_SUBST(extra_parts)
 AC_SUBST(asm_hidden_op)
Index: Makefile.in
===================================================================
--- Makefile.in	(revision 169877)
+++ Makefile.in	(working copy)
@@ -253,6 +253,16 @@ objects = $(filter %$(objext),$^)
 tmake_file = @tmake_file@
 include $(srcdir)/empty.mk $(tmake_file)
 
+# Collect target defines and headers from config.host.
+libgcc_tm_defines = @tm_defines@
+libgcc_tm_file = @tm_file@
+libgcc_tm.h: libgcc_tm.stamp; @true
+libgcc_tm.stamp:
+	DEFINES='$(libgcc_tm_defines)' HEADERS='$(libgcc_tm_file)' \
+		$(srcdir)/mkheader.sh > tmp-libgcc_tm.h
+	$(SHELL) $(srcdir)/../move-if-change tmp-libgcc_tm.h libgcc_tm.h
+	echo timestamp > $@
+
 # Only handle shared libraries if both:
 #   - the user requested them
 #   - we know how to build them
Index: config.host
===================================================================
--- config.host	(revision 169877)
+++ config.host	(working copy)
@@ -57,6 +57,8 @@
 asm_hidden_op=.hidden
 extra_parts=
 tmake_file=
+tm_defines=
+tm_file=
 
 # Set default cpu_type so it can be updated in each machine entry.
 cpu_type=`echo ${host} | sed 's/-.*$//'`
Index: mkheader.sh
===================================================================
--- mkheader.sh	(revision 0)
+++ mkheader.sh	(revision 0)
@@ -0,0 +1,41 @@
+#! /bin/sh
+
+# Copyright (C) 2001, 2002, 2006, 2007, 2010, 2011 Free Software Foundation, Inc.
+# This file is part of GCC.
+
+# GCC is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+
+# GCC is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.  
+
+
+# Print libgcc_tm.h to the standard output.
+# DEFINES and HEADERS are expected to be set in the environment.
+
+# Add multiple inclusion protection guard, part one.
+echo "#ifndef LIBGCC_TM_H"
+echo "#define LIBGCC_TM_H"
+
+# Generate the body of the file
+echo "/* Automatically generated by mkheader.sh.  */"
+for def in $DEFINES; do
+    echo "#ifndef $def" | sed 's/=.*//'
+    echo "# define $def" | sed 's/=/ /'
+    echo "#endif"
+done
+
+for file in $HEADERS; do
+    echo "#include \"$file\""
+done
+
+# Add multiple inclusion protection guard, part two.
+echo "#endif /* LIBGCC_TM_H"